1. Field of the Disclosure
The invention relates to the field of plug connectors, in particular plug connectors for optical cables.
2. Related Art
Plug connectors for optical cables are known from the prior art. So-called LC connectors are likewise known. In a further sense, these are push-pull connectors which have a high packing density. Corresponding connectors are manufactured by the applicant but are also available from a wide variety of other manufacturers.
European patents EP 0 762 558 B1 and EP 0 768 547 B1 describe an optical plug connector. The plug connector has a base body for accommodating the optical conductor. A structural extension member (also designated latching member or locking member) which is designed in an elastically resilient manner and has locking shoulders is integrally formed on the outside of the plug connector, the free end of said structural extension member being directed toward the rear end of the plug connector. A flange or trigger is also integrally formed on the outside of the plug connector, the free end of said flange or trigger pointing toward the front end of the plug connector in a manner protruding obliquely upward and interacting with the free end of the locking member. When the free end of the trigger, which is arranged in a fixed position, is depressed in an elastically resilient manner, the free end of the locking member is pressed toward the central axis and the plug connector can be pulled out of the socket by pulling the base body toward the rear if, or as long as, the trigger is simultaneously depressed in the process. One disadvantage is the unfavorable conduction of the forces: since a force which is directed forward is required for depressing the trigger, but a force which is directed toward the rear is required for removing the connector from a socket, the connector can be unlocked only with comparative difficulty.
European patent EP 1 091 227 B1 discloses a further design variant of a plug connector with a trigger which is fixed in position. A locking member is integrally formed on the base body. The plug connector also comprises a collar-like reinforcement element (designated yoke) with a square cross section which completely surrounds a subregion of the base body perpendicular to the central axis of the plug connector. A trigger, which is of elastically resilient design, is also integrally formed on the reinforcement element, the free end of said trigger—analogously to EP 0 762 558 B1 and EP 0 768 547 B1—interacting with the free end of the locking member which is integrally formed on the base body. During manufacture or assembly of the plug connector, the reinforcement element is pushed onto the base body along the central axis and fixed in a defined position. As in EP 0 762 558 B1 and EP 0 768 547 B1, the plug connector can be pulled out of the socket when the trigger is depressed onto the locking member and, at the same time, the plug connector or base body is pulled toward the rear.
U.S. Pat. No. 6,565,262 B2 discloses a further design variant of a plug connector with a trigger which is fixed in position. As in EP 1 091 227 B1, a locking member, which protrudes toward the rear in an oblique manner, is integrally formed on a base body of the plug connector, it being possible for said locking member to likewise be operated by a trigger. The trigger is integrally formed on a protective collar which is arranged in a fixed manner in the axial direction and has a substantially C-shaped cross section. The protective collar can be snapped onto the base body or the conductor both in a direction which is diverted away from the central axis, and also pushed toward and onto the base body in the direction of the central axis. In the functional position which meets requirements, the protective collar is mounted or positioned on the base body in a fixed manner; projections from the protective collar engage in corresponding cutouts in the base body. The plug connector can be removed from the collar when—as in the case of the preceding prior art—the trigger is pressed downward and the plug connector is pulled toward the rear at the same time. In this case, the protective collar is not displaced toward or in relation to the base body.
US patent application US 2004/0247252 A1 discloses a plug connector which consists of a base body and an unlocking element. The base body and the unlocking element are coupled to one another in an interlocking manner and are designed in such a way that an optical conductor can be received in the direction of the central axis. A locking member which protrudes obliquely toward the rear is fitted on the outside of the base body by means of a hinge. The base body also has, on the side, a continuous recess which interacts with a tongue of the unlocking element and determines the travel of the displacement between the base body and the unlocking element along the central axis. The unlocking element comprises a dimensionally stable structure which protrudes from the central axis and has a shaft which accommodates the free end of the locking member. When the unlocking element is pulled toward the rear along the central axis, the locking member is pressed against the base body and, in the process, unlocks the plug connector, and therefore the plug connector can be pulled out of the socket. In comparison to the prior art which is acknowledged above, the trigger does not have to be held in a depressed position as the plug connector is being pulled toward the rear, while the unlocking element—and not the basic housing—is pulled toward the rear. One disadvantage is that the unlocking element has a very complicated structure.
U.S. Pat. No. 6,752,538 B1, U.S. Pat. No. 6,821,024 B2 and U.S. Pat. No. 7,052,186 B1 each disclose a plug connector or a pair of coupled plug connectors having an apparatus which is intended to prevent unintentional unlocking. In order to prevent unintentional unlocking of the locking member, a securing collar, which can be displaced in the direction of the central axis, is mounted on the base body. The securing collar can firstly be pushed forward by way of the rear end of the operating element, so that the front end of the operating element engages beneath the locking member, therefore presses said locking member upward and additionally locks said locking member, that is to say protects it against being unintentionally released. If the securing collar is pushed toward the rear, the front end of the operating element is no longer positioned beneath the locking element, and this locking element can therefore be pressed downward in order to unlock the connector in the usual manner.
U.S. Pat. No. 5,984,531 discloses an optical connector which has an integrated cover which opens automatically when the connector is inserted and closes again when it is removed. An arm, which is mounted on the rear end of the housing and protrudes obliquely forward, serves as a locking member. A sleeve which is pressed into the housing from the rear as far as a stop and has an integrally formed crimping neck closes off the connector at the rear. At the same time, the sleeve serves as an abutment for supporting a spring which is arranged in the interior and is clamped between the sleeve and a ferrule holder and actively presses said sleeve forward.
U.S. Pat. No. 6,206,581 is directed at an optical connector with an integrally formed housing. A locking member is integrally formed on a side wall in the front region of the housing and protrudes upward and obliquely toward the rear. Said locking member is of resilient design and, in its rear region, can be pressed elastically against the side wall of the housing for unlocking purposes. In order to close the housing, a sleeve which is provided with laterally protruding locking elements is inserted into a longitudinal opening in the housing from the rear until the locking elements of the sleeve latch into correspondingly provided lateral openings in the housing. The cross section of the longitudinal opening is of rectangular or polygonal design at least at the rear end. In the rear region, the housing has slots which run in the longitudinal direction and allow the housing sides to be bent outward when the locking elements latch in. The cross section of the sleeve is designed such that the sleeve cannot rotate about its longitudinal axis in the latched-in state on account of its interlocking design. An unlocking element which is fitted onto the connector housing from the rear has an unlocking lug which protrudes obliquely forward and upward and can be pressed forward and downward onto the rear end of the locking element, so that said locking element is unlocked. Therefore, depending on the configuration, more than one connector can be unlocked at the same time. Further connectors of a similar nature are also known from U.S. Pat. No. 5,481,634 and, respectively, U.S. Pat. No. 5,579,425. The housings of these connectors are closed at the rear end by a correspondingly configured cover which is produced by injection molding.
One disadvantage of the solutions known from the prior art is the unfavorable conduction of forces during unlocking, and also the complicated structure. Many of the known connectors require two movements—the trigger being pressed downward and the plug connector being pulled toward the rear—to be performed approximately synchronously in order for said connectors to be released from the socket. Other plug connectors are distinguished by a complicated structure which has a disadvantageous effect on the manufacturing costs.